J. mar. biol. Ass. India, 47 (1) : 88 - 91, Jan. - June, 2005

NOTE

Encrusting form of coral as a biofouler in the marine environment of southeast coast of India

N. Marimuthu, J. Jerald Wilson and A.K. Kumaraguru

Centre for Marine and Coastal Studies, School of Energy, Environment and Natural Resources, Madurai Kamaraj University, Madurai - 625 021, India

Abstract

Encrusting form of coral Montipora sp. belonging to the family Acroporidae, was found to settle on vertically submerged biofouling test panels installed at Pudhumadam coastal waters in the Gulf of Mannar. No other types of corals were found to settle on these test panels. The recruitment and growth of the coral occurred during March and November. Only 2% of the total number of test panels showed coral attachment. A range of 7 - 15% of the surface area of the panels was covered by the coral growth. Out of four different types of test panels em- ployed, the one which was made of concrete, showed no coral settlement.

Knowledge of biofouling organisms has become important in view of the damages they cause to various fishing crafts, under water structures, objects and instruments that are employed or installed by man in the marine environment. The surfaces of these objects are used for settlement by a wide variety of organisms in the marine environment. The most commonly occur- ring foulers are barnacles, polychaetes, bivalves, sponges and algae. However, reports on corals as biofoulers are few (Callow, 1999). This is mostly due to the limitation in the distribution of corals to

fringing and patch reefs around them. The length of the coastline of the main- land in the vicinity of these islands is about 140 km between Rameswaram and Tuticorin with a number of fishing vil- lages. There are hundreds of fishing ca- noes and motorised medium size boats which encounter biofouling problem re- quiring periodic cleaning and mainte- nance. Since the Gulf of Mannar has a coral reef rich environment, there is every possibility of corals contributing to the biofouling problem. Therefore, a study on biofouling by corals was conducted.

certain areas of the marine realm. In coral This study was carried out with funds reef areas, larvae of corals may disperse provided by the Department of Ocean and On any substratum Development of the Government of India including man-made structures. through its Ocean Science and Technol-

Gulf of Mannar in the southeast coast ogy Cell based at Annamalai University of India has a chain of 21 islands with in Tamil Nadu. Ms. Jackie Wolstenholme

Encrusting form of coral as biofouler 89

of the museum of Tropical Queensland, was 60 meters. They were suspended Australia, identified the coral genus in vertically in such a way that one side of this study. the panel was facing seaward and the

Material and methods

Pudhumadam coast near Mandapam was chosen as the test site in the Gulf of Mannar (Fig. 1). This study was carried out for a period of one year from Novem- ber 16, 2002 to November 15, 2003. Four types of test panels were used viz., 1) plain Aini wood (Artocarpus hirsutus), 2) fibre coated Aini wood, 3) tar coated Aini wood and 4) concrete. The dimensions of the wood-based panels were 20 x 20 x 2.5 cm in length, breadth and width (LxBxW) and the concrete panels measured 20 x 20 x 1.25 cm.

An underwater biofouling panel sus- pension system was established (Marimuthu et al., 2004) at the study site in the coastal waters at Pudhurnadam for observing the attachment and accumula- tion of macrofoulers (Fig.1). The panels were vertically submerged under water at 2 meters depth where the total depth was 4 meters and the distance from the shore

PALK BAY

GULF OF MANNAR

79"05 79"20

other to the shore. Observations on the macrofoulers settled on both sides of the panels were made. The location of the biofouling test site was recorded using a Garmin model 12XL GPS (Lat. 09" 16.246' N., Long. 78" 59.847' E.).

A set of panels with duplicates of each type was immersed in the beginning (No- vember 16,2002) of the study period and new sets were added at fortnightly inter- vals. Thus, a total of 192 panels were immersed during the course of one-year period. At the end of the study period (November, 2003), all the panels were collected simultaneously and analyzed in the laboratory. Setting up and retrieval of the panels were done by SCUBA diving. The first set of panels immersed in the beginning would have been in the water for one whole year and the last set only for one fortnight. Immediately after re- trieving the test panels, those, which con- tained coral recruits, were labeled and washed in fresh water. The panels were then sun dried and all surfaces were searched for coral recruits. Surface area covered by corals was calculated follow- ing English et al. (1997).

Results and discussion

The study revealed that only one type of encrusting coral belonging to the fam- ily Acroporidae (Montipora sp.) was ob- served in the panels. Occasionally, encrust of this coral was also found on an oyster

Fig. 1. Biofouling study site at Pudhurnadam coast shell, Crassostrea sp, attached to the foul-

90 N. Marimuthu et al.

ing panel. Attachment was noticed only pied only 2% of the test panels. All the on the seaward side of the panels. (Fig.2). test panels were retrieved in November The different types of test panels contain- 2003. The settlement and subsequent ing the coral, the surface area covered growth of these corals should have oc- and the percentage covered on the sub- curred between March and November stratum are presented in Figure-3. The 2003. This indicated that the spawning coral settlement was observed in the wood, season of this coral is around the same tar coated and fibre coated panels sus- period. Harrison (1993) has also reported pended during March. Maximum surface that coral spawns during the full moon area covered (61.6cm2) was on the fibre period between October and December. coated wood pane' and minimum (7'3cm2) Although the depth, orientation of the On the Oyster attached to the tar and competition with other coated wood panel' These Occu- organisms are factors which affect the

- -~ -- --- recruitment rate of hard cor- . <

als (Banks and Harriott, 1996) the availability of coral spawn in a nearby location should also be considered. In the present case, the attach-

* ment of these corals on the

a h seaward side of the test pan- els, indicated that the cur- rents, the monsoon wind and wave action would have transported the larvae from the nearby Hare and Mulli islands, situated only 5 km away from the site. The

c d ~V*;T=*J 1 waters around these islands

4:. r . - are rich in a variety of corals. ',*+ g

There was no coral settle- ment on concrete panels in contrast with the other three types. This was perhaps due

P F to a large amount of bar- - 1 Fig. 2. (a) Clearing Biofoulers from a boat, (b) Fresh panels, nacles preferring concrete

(c, d 6 e) Encrusting form of Montipora sp. 0. Encrusting material and posing compe- "Aonitipora sp. on oyster shell tition for the attachment of

Encrusting form of coral as biofouler 91

70 1 Surface Area Covered 60 kS Percentage cover on panel 1 n

Wood Tar coated Fibre coated Substratum wood wood

Fig. 3. Surface Area Covered ( S A C ) by encrusting form of coral on biofouling panels '

other organisms including the corals. Mundy (2000) has also indicated that successful recruitment of corals depends on competitive interactions with other sessile organisms such as sponges, ascid- ians, bryozoans, etc. In general, corals are known to seek locations where there will be good light penetration, availability of clean, clear and warm water. Babcock and Smith (2000) have indicated that suspended sediments and silt in the water column may affect the coral population and symbiotic organisms by reducing light availability for photosynthesis. However, Pudhumadam coastal waters with rocky shoreline are relatively less disturbed and the location of biofouling test panel sys- tem about 60 meters away from the shore-

line might have given the conducive con- ditions for the settlement of coral larvae of the encrusting form. However, the fact that only 2% of the test panels could be occupied by the coral and that too an encrusting form which indicated that they face stiff competition from other biofoulers such as barnacles, polychaetes and bivalves.

References

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Banks, S.A. and V.J. Harriott. 1996. Coral Reefs 15 (4): 225-230.

Callow, M.E. 1999. The Status and Future of Bio- cides in Marine Biofouling Prevention. In: Fingerman, M., Nagabhushanam R. and Thompson M.F. (Eds.). Vo1.3: 109-126. Recent Advances in Marine Biotechnology; Biofilms, Bioadhesion, corrosion and Biofouling (vo1.3). Oxford & IBH Publishing Co. Pvt. Ltd. 312pp.

English, S., C. Wilkinson and V. Baker. 1997. Sur- vey manual for Tropical Marine Resources. Second edition. Australian Institute of Marine Science. 390pp.

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